Electrical motors are rated by their efficiency. Efficiency is simply the quotient of the mechanical power output, divided by the electrical power input.
  Efficiency  =            Mechanical      ⁢                          ⁢      power      ⁢                          ⁢      output              Electrical      ⁢                          ⁢      power      ⁢                          ⁢      input      To get a percent efficiency, the quotient is simply multiplied by 100.
      Percent    ⁢                  ⁢    Efficiency    =            (      100      )        ×                  Mechanical        ⁢                                  ⁢        power        ⁢                                  ⁢        output                    Electrical        ⁢                                  ⁢        power        ⁢                                  ⁢        input            
High efficiency motors that are on the market today, usually operate with efficiency maximums of about 97%. However, there are motors that have higher efficiencies. U.S. patents have been issued for devices that claim to approach efficiencies of 100%.
Since electric motors are used by the hundreds of millions in a myriad of applications even slight improvements in the efficiencies of electric motors save an enormous amount of electrical energy. Since much of this energy is generated from fossil fuels, increases in the efficiencies of electric motors have considerable positive environmental impacts.
Using electrical resonant circuits to drive or otherwise control electric motors is known, however these arrangements have drawbacks such as using a mandatory permanent magnet in the rotor and stator, which have fluxes that are alternatively shorted out and added to by a separate electromagnets in the rotor and stator; powering the motor with a DC battery, and having to adjust the motor's load or the capacitors to keep the machine at proper resonance.
Other prior art arrangements use brushless DC motors that have permanent magnets as rotors and use a LC resonant oscillator to constantly change the magnetic polarities of the stator poles in order to keep the rotor moving with the LC resonant oscillator alternatively switched on and off.
The prior art also includes single phase AC motors powered by parallel resonant circuits, and resonant series circuits as well as polyphase AC motors powered by quasi-parallel and series resonant circuits and by quasi-parallel and series resonant circuits.